Correct implementation of FlowReactor component name/index

include/cantera/zeroD/FlowReactor.h

@@ -103,12 +103,14 @@ class FlowReactor : public IdealGasReactor
         m_max_ss_error_fails = max_fails;
     }
 
-    //! Return the index in the solution vector for this reactor of the
-    //! component named *nm*. Possible values for *nm* are "X" (position),
-    //! "U", the name of a homogeneous phase species, or the name of a surface
+    //! Return the index in the solution vector for this reactor of the component named
+    //! *nm*. Possible values for *nm* are "density", "speed", "pressure",
+    //! "temperature", the name of a homogeneous phase species, or the name of a surface
     //! species.
     size_t componentIndex(const string& nm) const override;
 
+    string componentName(size_t k) override;
+
     void updateSurfaceState(double* y) override;
 
 protected:

src/zeroD/FlowReactor.cpp

@@ -342,21 +342,49 @@ void FlowReactor::getConstraints(double* constraints) {
 
 size_t FlowReactor::componentIndex(const string& nm) const
 {
-    // check for a gas species name
-    size_t k = m_thermo->speciesIndex(nm);
+    size_t k = speciesIndex(nm);
     if (k != npos) {
         return k + m_offset_Y;
-    } else if (nm == "rho" || nm == "density") {
+    } else if (nm == "density") {
         return 0;
-    } else if (nm == "U" || nm == "velocity") {
+    } else if (nm == "speed") {
         return 1;
-    } else if (nm == "P" || nm == "pressure") {
+    } else if (nm == "pressure") {
         return 2;
-    } else if (nm == "T" || nm == "temperature") {
+    } else if (nm == "temperature") {
         return 3;
     } else {
         return npos;
     }
 }
 
+string FlowReactor::componentName(size_t k)
+{
+    if (k == 0) {
+        return "density";
+    } else if (k == 1) {
+        return "speed";
+    } else if (k == 2) {
+        return "pressure";
+    } else if (k == 3) {
+        return "temperature";
+    } else if (k >= 4 && k < neq()) {
+        k -= 4;
+        if (k < m_thermo->nSpecies()) {
+            return m_thermo->speciesName(k);
+        } else {
+            k -= m_thermo->nSpecies();
+        }
+        for (auto& S : m_surfaces) {
+            ThermoPhase* th = S->thermo();
+            if (k < th->nSpecies()) {
+                return th->speciesName(k);
+            } else {
+                k -= th->nSpecies();
+            }
+        }
+    }
+    throw CanteraError("FlowReactor::componentName", "Index {} is out of bounds.", k);
+}
+
 }

test/python/test_reactor.py

@@ -1447,6 +1447,27 @@ def test_catalytic_surface(self):
         assert X == approx([0.01815402, 0.21603645, 0.045640395])
         assert r.thermo.density * r.area * r.speed == approx(mdot)
 
+    def test_component_names(self):
+        surf = ct.Interface('methane_pox_on_pt.yaml', 'Pt_surf')
+        gas = surf.adjacent['gas']
+        r = ct.FlowReactor(gas)
+        rsurf = ct.ReactorSurface(surf, r)
+        sim = ct.ReactorNet([r])
+        sim.initialize()
+
+        assert r.n_vars == 4 + gas.n_species + surf.n_species
+        assert sim.n_vars == r.n_vars
+
+        for i in range(r.n_vars):
+            name = r.component_name(i)
+            assert r.component_index(name) == i
+
+        with pytest.raises(IndexError, match="No such component: 'spam'"):
+            r.component_index('spam')
+
+        with pytest.raises(ct.CanteraError, match='out of bounds'):
+            r.component_name(200)
+
 
 class TestSurfaceKinetics(utilities.CanteraTest):
     def make_reactors(self):